Knowing that file transfer using any IM/Messenger system is VERY dangerous, ISP and network management have been adding filters, firewalls, and blocks to protect everyone for malicious attachments.
It used to work and now it doesn’t. “Contact your ISP or System Administrator.” Yes there is a new filter in your connection.
Executables (.exe or .bat or .vbs), pictures (.jpg or .mpg), and scripts (.js or .pl or .cgi) are the primary things being blocked.
Have your friend try ‘zipping’ the picture or try a plain text doucment. Then you would know if it is a total block or selective.
While not a solution I hope this gets you started. Good Luck.